Low overhead aperiodic triggering of multi-symbol SRS

Abstract

Systems and methods are disclosed herein for providing aperiodic Sounding Reference Signal (SRS) triggering in a wireless system. Embodiments of a method performed by a wireless device and corresponding embodiments of a wireless device are disclosed. In some embodiments, a method in a wireless device for triggering aperiodic SRS comprises receiving a first SRS configuration for a first type of aperiodic SRS transmission and a second SRS configuration for a second type of aperiodic SRS transmission. The method further comprises receiving downlink control information comprising a parameter for triggering an aperiodic SRS transmission and determining whether to use the first SRS configuration or the second SRS configuration. The method further comprises transmitting an aperiodic SRS transmission in accordance with the determined SRS configuration. Embodiments of a method performed by a base station and corresponding embodiments of a base station are also disclosed.

What is claimed is: 
     
       1. A method in a wireless device for triggering aperiodic Sounding Reference Signal, SRS, the method comprising:
 receiving a first SRS configuration for a first set of wireless device specific SRS uplink normal subframes and/or a second SRS configuration for a second set of wireless device specific uplink normal subframes; 
 receiving downlink control information in a first subframe to trigger an aperiodic SRS transmission in a second subframe, the received downlink control information comprises a parameter provided in a same-length SRS request field of the downlink control information for triggering the aperiodic SRS transmission using the first SRS configuration or the second SRS configuration; 
 determining whether to use the first SRS configuration or the second SRS configuration based on whether the second subframe is included in the first set of wireless device specific SRS uplink normal subframes or the second set of wireless device specific SRS uplink normal subframes and at least one of:
 one or more higher layer parameters configured to activate the first SRS configuration or the second SRS configuration; and 
 a Medium Access Control, MAC, Control Element, CE, configured to activate the first SRS configuration or the second SRS configuration; and 
 
 transmitting the aperiodic SRS transmission in accordance with the determined SRS configuration. 
 
     
     
       2. The method of  claim 1  wherein:
 the first SRS configuration is a configuration for transmission of: (a1) an SRS transmission in a last Single Carrier Frequency Division Multiple Access, SC-FDMA, symbol of a normal uplink subframe, (b1) an SRS sequence generated from a physical cell identity of a corresponding cell, or both (a1) and (b1); and 
 the second SRS configuration is a configuration for transmission of: (a2) an SRS transmission in more than one SC-FDMA symbol of a normal uplink subframe, (b2) an SRS sequence generated from a virtual cell identity, or both (a2) and (b2). 
 
     
     
       3. The method of  claim 1  wherein:
 the parameter comprised in the downlink control information for triggering an aperiodic SRS transmission is a multi-bit parameter comprising two or more bits, wherein a first value of the multi-bit parameter is mapped to the first SRS configuration and a second value of the multi-bit parameter is mapped to the second SRS configuration; and 
 determining whether to use the first SRS configuration or the second SRS configuration comprises determining whether to use the first SRS configuration or the second SRS configuration based on the multi-bit parameter and mappings between the first and second values of the multi-bit parameter and the first and second SRS configurations. 
 
     
     
       4. The method of  claim 1  wherein:
 the parameter comprised in the downlink control information for triggering an aperiodic SRS transmission is a multi-bit parameter comprising two or more bits, wherein a first value of the multi-bit parameter is mapped to the first SRS configuration and a second value of the multi-bit parameter is mapped to the second SRS configuration; 
 the value of the multi-bit parameter comprised in the downlink control information for triggering an aperiodic SRS transmission is the first value; and 
 determining whether to use the first SRS configuration or the second SRS configuration comprises determining to use the first SRS configuration based on the value of the multi-bit parameter and the mapping between the first value of the multi-bit parameter and the first SRS configuration. 
 
     
     
       5. The method of  claim 1  wherein:
 the parameter comprised in the downlink control information for triggering an aperiodic SRS transmission is a multi-bit parameter comprising two or more bits, wherein a first value of the multi-bit parameter is mapped to the first SRS configuration and a second value of the multi-bit parameter is mapped to the second SRS configuration; 
 the value of the multi-bit parameter comprised in the downlink control information for triggering an aperiodic SRS transmission is the second value; and 
 determining whether to use the first SRS configuration or the second SRS configuration comprises determining to use the second SRS configuration based on the value of the multi-bit parameter and the mapping between the second value of the multi-bit parameter and the second SRS configuration. 
 
     
     
       6. The method of  claim 1 , wherein the second subframe is a first available SRS subframe n+k, where n is a subframe number that corresponds to the first subframe and k is greater than or equal to a predetermined or signaled value k p . 
     
     
       7. The method of  claim 1  wherein:
 the first set of wireless device specific SRS uplink normal subframes and the second set of wireless device specific SRS uplink normal subframes are disjoint sets; and 
 determining whether to use the first SRS configuration or the second SRS configuration based on whether the second subframe is included in the first set of wireless device specific SRS uplink normal subframes or the second set of wireless device specific SRS uplink normal subframes comprises:
 determining to use the first SRS configuration if the second subframe is in the first set of wireless device specific SRS uplink normal subframes; and 
 determining to use the second SRS configuration if the second subframe is in the second set of wireless device specific SRS uplink normal subframes. 
 
 
     
     
       8. The method of  claim 1 , wherein:
 the first set of wireless device specific SRS uplink normal subframes and the second set of wireless device specific SRS uplink normal subframes overlap; 
 the second subframe is included in both the first set of wireless device specific SRS uplink normal subframes and the second set of wireless device specific SRS uplink normal subframes; and 
 determining whether to use the first SRS configuration or the second SRS configuration based on whether the second subframe is included in the first set of wireless device specific SRS uplink normal subframes or the second set of wireless device specific SRS uplink normal subframes comprises determining whether to use the first SRS configuration or the second SRS configuration based on a predefined or preconfigured rule that defines how collisions are to be handled. 
 
     
     
       9. The method of  claim 1 , wherein:
 the first set of wireless device specific SRS uplink normal subframes and the second set of wireless device specific SRS uplink normal subframes overlap; 
 the second subframe is included in both the first set of wireless device specific SRS uplink normal subframes and the second set of wireless device specific SRS uplink normal subframes; and 
 determining whether to use the first SRS configuration or the second SRS configuration based on whether the second subframe is included in the first set of wireless device specific SRS uplink normal subframes or the second set of wireless device specific SRS uplink normal subframes comprises determining whether to use the first SRS configuration or the second SRS configuration based on priorities associated with the first SRS configuration and the second SRS configuration or based on periodicities of the first SRS configuration and the second SRS configuration. 
 
     
     
       10. The method of  claim 1  further comprising:
 receiving an indication to use an indicated type of aperiodic SRS triggering, the indicated type of aperiodic SRS triggering being a first type of aperiodic SRS triggering or a second type of aperiodic SRS triggering; 
 wherein determining whether to use the first SRS configuration or the second SRS configuration comprises determining whether to use the first SRS configuration or the second SRS configuration based on the indication. 
 
     
     
       11. The method of  claim 10  wherein receiving the indication comprises receiving the indication via higher layer signaling. 
     
     
       12. The method of  claim 10  wherein receiving the indication comprises receiving the indication via a Medium Access Control, MAC, Control Element, CE. 
     
     
       13. A wireless device for triggering aperiodic Sounding Reference Signal, SRS, wherein the wireless device comprises:
 one or more transmitters; 
 one or more receivers; and 
 processing circuitry associated with the one or more transmitters and the one or more receivers, the processing circuitry configured to cause the wireless device to:
 receive a first SRS configuration for a first set of wireless device specific SRS uplink normal subframes and/or a second SRS configuration for a second set of wireless device specific uplink normal subframes; 
 receive downlink control information in a first subframe to trigger an aperiodic SRS transmission in a second subframe, the received downlink control information comprises a parameter provided in a same-length SRS request field of the downlink control information for triggering the aperiodic SRS transmission using the first SRS configuration or the second SRS configuration; 
 determine whether to use the first SRS configuration or the second SRS configuration based on whether the second subframe is included in the first set of wireless device specific SRS uplink normal subframes or the second set of wireless device specific SRS uplink normal subframes and at least one of:
 one or more higher layer parameters configured to activate the first SRS configuration or the second SRS configuration; and 
 a Medium Access Control, MAC, Control Element, CE, configured to activate the first SRS configuration or the second SRS configuration; and 
 
 transmit the aperiodic SRS transmission in accordance with the determined SRS configuration. 
 
 
     
     
       14. A method performed by a base station for triggering aperiodic Sounding Reference Signal, SRS, comprising:
 transmitting, to a wireless device, a first SRS configuration for a first set of wireless device specific SRS uplink normal subframes and/or a second SRS configuration for a second set of wireless device specific uplink normal subframes; 
 transmitting, to the wireless device, downlink control information in a first subframe to trigger an aperiodic SRS transmission in a second subframe, the received downlink control information comprises a parameter provided in a same-length SRS request field of the downlink control information for triggering the aperiodic SRS transmission using the first SRS configuration or the second SRS configuration; and 
 receiving, from the wireless device, an aperiodic SRS transmission in accordance with one of the first and second SRS configurations determined based on whether the second subframe is included in the first set of wireless device specific SRS uplink normal subframes or the second set of wireless device specific SRS uplink normal subframes and at least one of:
 one or more higher layer parameters configured to activate the first SRS configuration or the second SRS configuration; and 
 a Medium Access Control, MAC, Control Element, CE, configured to activate the first SRS configuration or the second SRS configuration. 
 
 
     
     
       15. The method of  claim 14  wherein:
 the first SRS configuration is a configuration for transmission of: (a) an SRS transmission in a last Single Carrier Frequency Division Multiple Access, SC-FDMA, symbol of a normal uplink subframe and/or (b) an SRS sequence generated from a physical cell identity; and 
 the second SRS configuration is a configuration for transmission of: (a) an SRS transmission in more than one SC-FDMA symbol of a normal uplink subframe and/or (b) an SRS sequence generated from a virtual cell identity. 
 
     
     
       16. The method of  claim 14  wherein:
 the parameter comprised in the downlink control information for triggering an aperiodic SRS transmission is a multi-bit parameter comprising two or more bits, wherein a first value of the multi-bit parameter is mapped to the first SRS configuration and a second value of the multi-bit parameter is mapped to the second SRS configuration; and 
 receiving, from the wireless device, the aperiodic SRS transmission in accordance with one of the first and second SRS configurations comprises receiving, from the wireless device, the aperiodic SRS transmission in accordance with the value of the multi-bit parameter and mappings between the first and second values of the multi-bit parameter and the first and second SRS configurations. 
 
     
     
       17. The method of  claim 14  wherein:
 the parameter comprised in the downlink control information for triggering an aperiodic SRS transmission is a multi-bit parameter comprising two or more bits, wherein a first value of the multi-bit parameter is mapped to the first SRS configuration and a second value of the multi-bit parameter is mapped to the second SRS configuration; 
 the value of the multi-bit parameter comprised in the downlink control information for triggering an aperiodic SRS transmission is the first value; and 
 receiving, from the wireless device, the aperiodic SRS transmission in accordance with one of the first and second SRS configurations comprises receiving, from the wireless device, the aperiodic SRS transmission in accordance with the mapping between the first value of the multi-bit parameter and the first SRS configuration. 
 
     
     
       18. The method of  claim 14  wherein:
 the parameter comprised in the downlink control information for triggering an aperiodic SRS transmission is a multi-bit parameter comprising two or more bits, wherein a first value of the multi-bit parameter is mapped to the first SRS configuration and a second value of the multi-bit parameter is mapped to the second SRS configuration; 
 the value of the multi-bit parameter comprised in the downlink control information for triggering an aperiodic SRS transmission is the second value; and 
 receiving, from the wireless device, the aperiodic SRS transmission in accordance with one of the first and second SRS configurations comprises receiving, from the wireless device, the aperiodic SRS transmission in accordance with the mapping between the second value of the multi-bit parameter and the second SRS configuration.